Mining underground formations

ABSTRACT

Mining systems include a continuous miner; a movable roof support; a roof bolter; and a flexible conveyor train positioned with its front end located under the roof support and extending underneath the roof bolter.

CLAIM OF PRIORITY

This application claims priority under 35 USC § 119(e) to U.S. Patent Application Ser. No. 62/444,298, filed on Jan. 9, 2017 and 62/511,229, filed on May 25, 2017, the entire contents of each application is hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to mining underground formations, and more particularly to systems and methods for mining underground formations.

BACKGROUND

Continuous miners are typically machines with a large rotating steel drum equipped with tungsten carbide picks that rip material (e.g., coal) from an underground formation (e.g., a coal seam). Continuous miners account for about 45 percent of underground coal production. Conveyors transport the removed coal from the seam. Remote-controlled continuous miners are used to work in a variety of difficult seams and conditions, and robotic versions controlled by computers are becoming increasingly common. Continuous mining is a misnomer, as room and pillar coal mining is very cyclical. In the US, one can generally cut ˜20-35 feet (˜6-12 meters) before the continuous miner backs out and the roof is supported by a roof bolter, after which, the face has to be serviced, before it can be advanced again. During servicing, the “continuous” miner moves to another face. Some continuous miners can bolt the face while cutting coal. Most continuous mining machines in use in the US lack the ability to bolt. This may partly be because incorporation of bolting makes the machines wider, and therefore, less maneuverable.

A roof bolter is a rubber tired or cat-driven machine used to install rock bolts in mines, tunnels, underground power plants, and storage facilities. Roof bolting is also a common application in underground coal mines for securing mine roofs to be self-supportive. It is extremely dangerous as an occupation, accounting for nearly 56 percent of injuries in underground coal mining operations.

SUMMARY

Methods and equipment have been developed that can provide increased production relative to conventional continuous miner/bolter methods and systems. In addition, these methods and systems can also increase the safety of equipment operators relative to conventional miner/bolter methods and systems. These methods and equipment can combine the use of canopies, roof bolters, continuous miners, and flexible conveyor trains.

In one aspect, mining systems include: a continuous miner; a movable roof support; a roof bolter; and a flexible conveyor train positioned with its front end located under the roof support and extending underneath the roof bolter. Embodiments of mining systems can include one or more of the following features.

In some embodiments, the roof support includes: two tracks; legs mounted on the two tracks; and a canopy supported by legs and the two tracks; wherein the legs and the tracks are spaced apart to define a gap that is wide enough to receive the flexible conveyor train through the gap. In some cases, the gap is at least 14 feet (4.3 meters). In some cases, the legs comprise hydraulic pistons. In some cases, the moveable roof support is a first roof support and the mining system includes a second moveable roof support. The system can include chains extending between a canopy of the first moveable roof support and a canopy of the second moveable roof support. In some cases, the moveable roof support comprises a canopy and an extendable portion movable between an extended position and a retracted position by a piston.

In some embodiments, the roof bolter includes: two tracks; a canopy supported by the two tracks; wherein the tracks are spaced apart to define a gap that is wide enough to receive the flexible conveyor train through the gap. In some cases, the gap is at least 14 feet (4.3 meters). In some cases, the roof bolter comprises six drill masts. In some cases, the canopy is supported by legs mounted on the two tracks. In some cases, the legs comprise hydraulic pistons. In some cases, the canopy is supported by a scissors lift system mounted on the two tracks. In some cases, the canopy comprises a work platform. In some cases, the roof support comprises four drill masts pivotably mounted to the working platform and oriented upwards to install roof bolts. In some cases, the roof support comprises two drill masts that are pivotably mounted to the working platform and oriented sideways to install rib bolts.

In some aspects, methods of mining include: positioning a first movable roof support between a continuous miner and a roof bolter; and extending a flexible conveyor train between tracks of the roof bolter and between tracks of the first movable roof support and positioning a hopper of the flexible conveyor train to receive output of the continuous miner.

In operation, these systems and methods facilitate mining a deeper cut than conventional systems while providing roof and rib protection to the operators

The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are, respectively, a plan view and a profile view of a mining system.

FIGS. 2A and 2B are, respectively, a plan view and a profile view of a mining system.

FIGS. 3A and 3B are, respectively, a plan view and a profile view of a roof support.

FIGS. 4A and 4B are, respectively, a plan view and a profile view of paired roof supports.

FIGS. 5A, 5B, and 5C are, respectively, a plan view, a profile view (separated), and a profile view (together) of paired roof supports.

FIGS. 6A and 6B are, respectively, a plan view and a profile view of a roof bolter.

FIG. 7 is an end view of a roof bolter.

FIGS. 8A and 8B are perspective views of a continuous miner.

FIG. 9 is a perspective view of a flexible conveyor train.

FIG. 10 is a cut sequence for an advancing mining sequence.

FIGS. 10A-10I are plan views of an advancing mining sequence.

FIG. 11 is a cut sequence for a retreating mining sequence.

FIGS. 11A-11G are plan views of a retreating mining sequence.

FIG. 12 is a cut sequence for a retreating mining sequence.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Methods and equipment have been developed that can provide increased production relative to conventional miner/bolter methods and systems. In addition, these methods and systems can also increase the safety of equipment operators relative to conventional miner/bolter methods and systems. These methods and equipment can combine the use of roof supports, roof bolters, continuous miners, and flexible conveyor trains. We discuss examples of these methods and equipment in the context of extracting coal from a coal bed but they can be applied to other mining applications including, for example, mining trona, gypsum, potash and salt.

FIGS. 1A and 1B illustrate a mining system 100 that can be deployed, for example, off a surface mine highwall or from previously developed underground workings. The mining system 100 includes a continuous miner 110, two roof supports 112, and a roof bolter 114. A flexible conveyor train 116 is positioned with its front end 118 located under the canopy of the roof support 112 and extends underneath the roof bolter 114. The roof support 112 and the roof bolter 114 both have split bases (e.g., tracks and hydraulic jacks that straddle the flexible conveyor train 116.

FIGS. 2A and 2B illustrate a mining system 100′ that is substantially similar to the mining system 100 but only includes one roof supports 112. Both the mining system 100 and the mining system 100′ can provide increased production and safety relative to conventional miner/bolter methods and systems but the mining system 100 is anticipated to provide more operational flexibility than the mining system 100′.

In operation, these systems and methods facilitate mining a deeper cut than conventional systems while providing roof and rib protection to the operators. The independent operation of the continuous miner 110, the roof support(s) 112, and the roof bolter 114 balances out the inherent imbalance between the cutting/loading cycle and the roof support cycle. To achieve mining without stopping for roof bolting, it is necessary to install four roof bolts in approximately the time it takes to mine ahead 4 feet (1.2 meters) with the continuous miner. Mining ahead 4 feet (1.2 meters) is about two sump cycles (e.g., sump, rip/load, set over, sump, rip/load then clean up each side) of the continuous miner 110. It is anticipated that operators of the roof bolter 114 can install four roof bolts in approximately the same time as required for a cutting/loading/cleanup/set over cycle of the continuous miner 110. In the event that operators are not able to install four bolts, move up the roof bolter 114 and the roof support 112 in the same amount of time as the sump cycle, the roof support 112 provides the “lost motion” time. By driving straight ahead, these systems and methods provide long (e.g., hundreds of feet) uninterrupted runs for the mining and give the option to retreat by shortwall, longwall or slabbing/pillar recovery from a surface mine highwall or previously developed deep mine entries.

FIGS. 3A and 3B illustrate the roof support 112 in more detail. The roof support 112 includes a canopy 120 that is supported by four legs 122 (e.g., hydraulic jacks) mounted on two tracks 124. The legs 122 and the tracks 124 are spaced apart to define a gap 126 that is wide enough to receive the flexible conveyor train 116 and/or the continuous miner between the legs 122 and the tracks 124. Similarly, the roof supports 112 have a height measured to the underside of the canopy of ˜6.5 feet (˜2 meters) during mining operations.

For example, the roof support 112 has tracks 124 that are 2 feet (0.6 meters) wide and spaced 14.5 feet (4.4 meters) apart. This configuration provides a gap between the tracks 124 that is wide enough to receive standard continuous miners which are 11.5 feet (3.5 meters) wide with a clearance of 1.5 feet (0.5 meters) on either side of the continuous miner. The feeder/breaker and the body of the flexible conveyor train 116 are typically ˜7 feet (˜2.1 meters) wide and 5 feet (1.5 meters) wide, respectively, and easily pass between the tracks 124 of the roof support 112. The flexible conveyor train 116 typically has a height of approximately 5 feet (1.5 meters) and the continuous miner 110 typically has a height of ˜6 feet (˜1.8 meters). This configuration enables the roof support 112 to straddle both the continuous miner 110 and the flexible conveyor train 116 and pass over the continuous miner 110. Some mining systems 100 use roof supports 112 that have legs and tracks that are spaced far enough apart (e.g., 7.5 feet (2.3 meters), 8 feet (2.4 meters), 8.5 feet (2.6 meters)) to straddle the flexible conveyor train 116 but not the continuous miner 110.

Some systems are configured to use rubber tired mined material haulage equipment rather than a flexible conveyor train to transport mined material away from the continuous miner 110. In these systems, the roof support 112 may be wider to accommodate the rubber tired mined material haulage equipment. Some systems use roof supports and/or roof bolters that are mounted on rubber tires rather than tracks.

Under permanently supported roof (e.g., bolted roof), the roof supports 112 can be used as a canopy rather than being pressurized against roof. This provides additional protection for miners while avoiding damage to the permanent roof support. In unsupported sections, the roof supports 112 can be pressurized against roof.

The legs 122 (e.g., hydraulic jacks) of the roof support 112 hydraulically telescope to raise the canopy into contact with the roof of the mine. Some roof supports 112 are configured to provide a false roof effect without being raised into contact with the roof of the mine. The canopy 120 of the roof support 112 provides protection from falling roof and rib material, enables a much deeper cut, and reduces the need to change from one entry to another.

Some roof supports 112 incorporate a motor operable to drive the tracks 124. Some roof supports 112 include rib protection such as, for example, heavy chains hanging down from the side edges of the canopy.

Using a pair of roof supports 112 with one roof support 112 moving with the continuous miner 110 and one roof support 112 moving with the roof bolter 114 further decouples the advance of the continuous miner 110 from the advance of the roof bolter 114 to increase operational flexibility and speed of mining. Some roof supports include features configured to provide roof protection in gaps that can develop between the main canopies of the roof supports due to the different speeds of advance of the continuous miner and the roof bolter.

FIGS. 4A and 4B show a pair of roof supports 113. Each roof support 113 is substantially similar to the roof support 112 but includes a canopy 120 with an extendable portion 121 and a hydraulic piston 123. If a gap starts to develop between the main canopies of the roof support 113 moving with the continuous miner 110 and the roof support 113 moving with the roof bolter 114, the hydraulic piston 123 extends to deploy the extendable portion 121 of one or both roof supports 113.

FIGS. 5A-5C show a pair of roof supports 115. Each roof support 115 is substantially similar to the roof support 112. The pair of roof supports 115 are joined by chains 117 that extend between the canopies of the roof supports. The chains 117 provide protection if a gap starts to develop between the main canopies of the roof support 115 moving with the continuous miner 110 and the roof support 115 moving with the roof bolter 114 (see FIGS. 5A and 5B). When a gap starts to develop between the main canopies of the roof supports 115, the chains 117 stretch between the canopies 120 of the roof supports 115. Unlike the roof supports 113, the roof supports 115 are physically linked. The linkage between roof supports 115 may provide better roof protection at a cost of reduced operational flexibility relative to the roof supports 113.

FIGS. 6A and 6B illustrate the roof bolter 114 in more detail. The roof bolter 114 includes a working platform 128. Like the canopy 120 of the roof support, the working platform 128 is supported by four legs 122 mounted on two tracks 124. The legs 122 and the tracks 124 are spaced apart to define a gap 126 that is wide enough to receive the flexible conveyor train 116 and/or the continuous miner between the legs 122 and the tracks 124. This configuration enables the roof bolter 114 to straddle both the continuous miner 110 and the flexible conveyor train 116 and pass over the continuous miner 110. Some systems are configured to use rubber tired mined material haulage equipment such as, for example, shuttle cars or ram cars, rather than a flexible conveyor train to transport mined material away from the continuous miner 110. In these systems, the roof bolter 114 may be wider (e.g., define a gap of 11.5 feet (3.5 meters), 12 feet (3.7 meters), 13 feet (4 meters), or more) to accommodate the rubber tired mined material haulage equipment. The legs 122 of the roof bolter 114 hydraulically telescope to raise the working platform into position for roof bolts to be installed into the roof of the mine. Depending on the entry height, the operators of the roof bolter 114 can be on top of or underneath the working platform 128. The canopy 120 of the roof support 112 provides protection in front of the roof bolter 114.

The work platform 128 also functions as a canopy for workers under the work platform. Some roof bolters include a frame that is more robust than a normal portal type canopy. The drill masts 132 are hung from the canopy of the working platform 128. The roof bolter 114 includes four drill masts 132 that are pivotably mounted to the working platform and generally oriented upwards to install roof bolts. The roof bolter 114 includes two drill masts 132 (one on each side) that are pivotably mounted to the working platform and generally oriented sideways to install rib bolts.

Operators can move across the front of the work platform 128 when performing roof bolting. Three operators are anticipated to operate the roof bolter 114—one operator installing bolts with the left two roof drill masts and the left rib drill mast, one operator installing bolts with the right two roof drill masts and the right rib drill mast, and a helper. This manning combined with the configuration of the roof bolter 114 is anticipated to enable mining sequence described in this disclosure.

Using a follow-on roof bolter in this fashion enables bolting to occur quicker than a place change system in which a continuous miner is withdrawn from a face and replaced by a roof bolter while affording additional protection for the operators of the roof bolter 114. The roof support 112 provides temporary roof support for the operators of the roof bolter 114. By delinking the roof bolter function from the mining and conveying functions provides for increased production over systems in which roof bolters are mounted on continuous miners.

Some roof bolters include an electric motor to move the roof bolter, hydraulic pumps to raise and lower the work platform, blowers and a dust box. A prepackaged box 130 holds roof bolting supplies. It is anticipated that the working platform 128 will hold two or more shifts worth of roof bolting supplies in the prepackaged box 130. As illustrated, the prepackaged box 130 sits on top of the work platform 128 of the roof bolter 114. This configuration is typically used when the mining height is 10-18 feet (3-5.5 meters). When the mining height is less than 10 feet (3 meters), the prepackaged box 130 is typically slung underneath the work platform 128 of the roof bolter 114. The ability of the roof bolter 114 to tram over the flexible conveyor train 116 facilitates resupply. To resupply, the roof bolter 114 trams back to a crosscut where, for example, a diesel forklift removes the depleted supply box and loads a fresh prepackaged supply box from the crosscut. Such resupply is typically done during power and belt moves to limit impacts on mining operations.

FIG. 7 illustrates a roof bolter 144 that is generally similar to the roof bolter 114. However, the roof bolter 144 includes a scissors lift system 146 rather than the hydraulic jacks of roof bolter 114. The work platform 128 of the roof bolters is not required to support the roof so hydraulic jacks are not required.

FIGS. 8A and 8B illustrate the continuous miner 110 in more detail. The continuous miner 110 has a large rotating steel drum 134 equipped with tungsten carbide teeth 136 that rip coal from the coal face. Continuous miners are traditionally used in a “room and pillar” mining system where the mine is divided into a series of 18-to-20 foot (5.5-to-6.1 meter) “rooms” or work areas cut into the coal bed. A continuous miner can mine as much as 38 short tons of coal a minute, and can remove swaths of material approximately 11.5 feet (3.5 meters) wide. Continuous miners can utilize, for example, conveyors, ram cars or shuttle cars to transport the removed coal from the coal face, and unlike the shearers often used in longwall mining operations, is independently mobile rather than carried or otherwise conveyed along the length of the coal face.

A trailing cable 138 (see FIG. 8B) provides power to the continuous miner 110. The cable can be carried and deployed from the flexible conveyor train 116. The operator controls the continuous miner by wireless systems. The water is supplied to the continuous miner through a separate water hose, which can also be mounted on the flexible conveyor train 116.

FIG. 9 illustrates the flexible conveyor train 116 in more detail. The material extracted by the continuous miner 110 is loaded into a hopper 140 located at the front end of the flexible conveyor train 116. The flexible conveyor train removes the received material from the face by conveying it via a conveyor belt 142 running along the length of the flexible conveyor train 116. Receiving the coal from the continuous miner 110 and transports the coal, for example, to a fixed section belt for removal from the mine, the flexible conveyor train 116 reduces the total number of mobile machines (e.g., shuttle cars) and workers in the mine. Higher capacity production is also possible as the continuous haulage eliminates the bottle necks and wait times during batch haulage systems. In addition, material degradation is reduced with the reduction of transfer points improving product quality while reducing dust and improving safety. Flexible conveyor trains are typically provided with radio remote controls similar to the continuous miners.

In operation, the systems and methods described above facilitate mining a deeper cut than conventional systems while providing roof and rib protection to the operators. The independent operation of the roof support 112 and the roof bolter 114 balances out the inherent imbalance between the cutting/loading cycle and the roof support cycle. To achieve mining without stopping for roof bolting, it is necessary to install four roof bolts in approximately the time it takes to mine ahead 4 feet (1.2 meters) with the continuous miner. Mining ahead 4 feet (1.2 meters) is about two sump cycles (e.g., sump, rip/load, set over, sump, rip/load then clean up each side) of the continuous miner 110. It is anticipated that operators of the roof bolter 114 can install four roof bolts and two rib bolts in approximately the same time as required for a cutting/loading/cleanup/set over cycle of the continuous miner 110. In the event that operators are not able to install the bolts, move up the roof bolter 114 and the roof support 112 in the same amount of time as the sump cycle, the roof support 112 provides the “lost motion” time. By driving straight ahead like, these systems and methods provide long (e.g., thousands of feet) uninterrupted runs for the mining and give the option to retreat by shortwall, longwall or slabbing/pillar recovery from a surface mine highwall or previously developed deep mine entries.

FIG. 10 shows a cut sequence for using an embodiment of the mining system 100 to develop a mine 200. The mine 200 includes a No. 1 entry (left entry) 150, a No. 2 entry (center entry) 152, and a No. 3 entry (right entry) 154. FIGS. 10A-10I illustrate implementation of this embodiment of the mining system 100. Although the mine 200 has a three-entry system, other mines may have different numbers of entries depending on factors including, for example, the flexible conveyor train limitations and ventilation requirements.

In FIG. 10, faces 157 of the entries are indicated by dashed lines. The cuts are indicated by numbered arrows in the entries and crosscuts. As shown in FIG. 10A, the continuous miner 110, the roof support 112, the roof bolter 114, and the flexible conveyor train 116 are initially located in the middle entry 152 outby the crosscut to be mined next. When mined, this crosscut is part of Cut #1 (FIG. 10).

An independent mobile roof bolter 148 is located in the left entry 150 and another independent roof bolter 148 is located in the right entry 154. Each of the entries has a width W1 of ˜18 feet (˜5.5 meters) and the entries are separated from each other by a width W2 of ˜65 feet (˜20 meters) of the formation being mined. The mobile roof bolters 148 are used to install roof bolts 156 in the ends of the left entry 150 and the right entry 154. These roof bolts 156 are not shown in FIGS. 10B-10I to make it easier to see other system components.

Cut #1 (FIG. 10) is mined and bolted to the left until it cuts through the bolted left entry 150. The roof supports 112 and the roof bolter 114 follow the continuous miner 110 with the roof supports 112 and the roof bolter 114 straddling the flexible conveyor train 116 (FIG. 10B). The crosscut is ˜75 feet (˜23 meters) long and the crosscut and No. 2 entry define an angle λ of ˜60-75 degrees.

The continuous miner 110, the roof support 112, and the roof bolter 114 are operated in the cutting/loading cycle and the roof support cycle described above during the advance. The roof supports 112 function as a canopy (i.e., they are not pressurized against the roof while under the bolted entry). The roof supports 112 are only pressurized as they advance under the unbolted roof. The roof bolter 114 follows along bolting the unsupported roof as it becomes mined.

The second roof support 112 functions as the temporary roof support for the bolting function. In some systems, the roof bolter 114 also includes integrated temporary roof support components. This approach frees up the second roof support 112 to continue on with the other roof support 112 and the continuous miner 110.

Cut #1 (FIG. 10) is continued to extend the No. 1 entry. The continuous miner 110, the roof supports 112, and the roof bolter 114 continue to mine and bolt up the left entry 150 for a distance that places the face 20 feet (˜6 meters) past the next crosscut to be developed (i.e., when Cut #4 is made). In this illustrated layout, this continuation of Cut #1 extends the left-hand entry ˜100 feet (˜30 meters) from the initial crosscut.

After Cut #1 is completed, the continuous miner 110, the roof supports 112, the roof bolter 114, and the flexible conveyor train 116 are then retreated back to the middle entry 152. When the advance is stopped, the roof bolter 114 is separated from the end of the entry by the roof supports 112 and the continuous miner 110. The conventional roof bolter 148 bolts the last 50-55 feet (˜15-17 meters) of the No. 1 entry left unbolted due to this separation after the continuous miner 110, the roof support 112, the roof bolter 114, and the flexible conveyor train 116 retreat back to the middle entry 152.

Cut #2 (FIG. 10) is mined and bolted to the left until it cuts through the bolted right-hand entry and extends the right-hand entry in the same manner that the Cut #1 was mined and bolted (FIG. 10C). After Cut #2 is completed, the continuous miner 110, the roof supports 112, the roof bolter 114, and the flexible conveyor train 116 are then retreated back to the middle entry 152.

Cut #3 (FIG. 10) is mined and bolted to extend the middle entry 152. The continuous miner 110, the roof supports 112, and the roof bolter 114 mine and bolt the middle entry 152 past where the next crosscuts will be turned (FIG. 10D). The middle entry is mined and bolted at least 10 feet (˜3 meters) past where the next crosscuts are to be turned left in Cut #4 and right in Cut #5. This leaves 30-35 feet (˜9-11 meters) of unsupported roof inby the crosscuts that will be bolted by the conventional roof bolter (148) as soon as practicable during the mining of Cut 4 or Cut 5.

The independent mobile roof bolter 148 from the left entry 150 can be used to bolt the unsupported roof at the end of the middle entry 152. The continuous miner 110, the roof support 112, the roof bolter 114, and the flexible conveyor train 116 start the crosscut to the right entry 154. In some cut sequences, the order of forming the crosscuts is reversed and the independent mobile roof bolter 148 from the right entry 154 is used to bolt the unsupported roof at the end of the middle entry 152.

FIG. 10F-10H illustrate one approach to using independent mobile roof bolter 148 from the left entry 150 to bolt the unsupported roof at the end of the middle entry 152. When the crosscut is long enough to receive the continuous miner 110, the roof support 112, and the roof bolter 114, the flexible conveyor train 116 retreats into the middle entry 152 outby the intersection of the crosscuts and the middle entry 152. The independent mobile roof bolter 148 from the left entry 150 moves though the cleared intersection of the crosscuts and the middle entry 152. After the independent mobile roof bolter 148 enters the No. 2 entry inby the intersection, the flexible conveyor train 116 and the roof bolter 114 advance into the crosscut to rejoin the continuous miner 110 and the roof support 112. The continuous miner 110, the roof support 112, the roof bolter 114, and the flexible conveyor train 116 finish the crosscut and extend the right entry 154 while the independent mobile roof bolter 148 bolts the unsupported roof at the end of the middle entry 152.

As shown in FIGS. 10H and 10I, the continuous miner 110, the roof support 112, the roof bolter 114, and the flexible conveyor train 116 retreat into the middle entry 152 outby the intersection after extending the right entry 154. After the continuous miner 110 clears the right entry 154, the independent mobile roof bolter 148 moves up and bolts the unsupported roof at the end of the right entry 154. After the continuous miner 110 clears the intersection between the crosscuts and the middle entry 152, the other independent mobile roof bolter 148 moves back to the left entry 150. That independent mobile roof bolter 148 bolts the unsupported roof at the end of the left entry 150 while the continuous miner 110, the roof support 112, the roof bolter 114, and the flexible conveyor train 116 repeat the steps of extending the No. 2 entry and forming the next crosscut.

Cut #4, Cut #5, and Cut #6 (FIG. 10) are mined and bolted similar manner as Cut #1, Cut #2, and Cut #3 (FIGS. 10E-10F). As shown in FIG. 10E, when repeating the sequence of forming a crosscut and extending the No. 1 entry in Cut #4, completion of the crosscut isolates a trapezoidal pillar in the formation that is ˜100 feet (˜30 meters) long and ˜65 feet (˜20 meters) wide. The iteration of the cut sequences can be continued to extend the entries into the formation being mined (see, for example, Cut #7, Cut #8, and Cut #9 in FIG. 10).

FIGS. 10A-10I illustrate an embodiment of the mining system 100 that includes two roof supports 112 between the continuous miner 110 and the roof bolter 114. Single roof supports such as, for example, those shown in FIGS. 2A and 2B could also be used. The paired roof supports provide operational flexibility but can result in additional roof unsupported at the end of the entries when the mining system retreats away from a face.

FIG. 11 shows a cut sequence for using an embodiment of the mining system 100 to mine the panel developed in the sequence illustrated in FIGS. 10A-10I. FIGS. 11A-11G illustrate mining the panel developed in the sequence illustrated in FIGS. 10A-10I. The continuous miner 110 and the flexible conveyor train are used in this retreat mining sequence. The illustrated sequence uses two roof supports 112 to extend the length of cuts off the entries while maintaining overhead protection without requiring additional roof bolting. The roof bolter 114 used in the advance is removed before beginning the retreat sequence.

FIG. 11A shows a three-entry system with the continuous miner 110 and two roof supports 112 deployed in the left entry 150. The flexible conveyor train 116 extends from the middle entry 152, through a crosscut, and up the left entry 150 through the two roof supports 112 to the continuous miner 110. Pairs of mobile roof supports 149 deployed in each of the entries 150, 152, 154. The middle entry 152 extends to a bleed air shaft 190.

FIG. 11B shows the initial cuts (Cut #1-Cut #5 in FIG. 11) being made by the continuous miner 110. The first cut is to the top left. Terms of orientation are used to indicate position relative to the figures being described rather than absolute orientation. The protection of the two roof supports 149 allow the continuous miner to advance ˜50-60 feet (15.2-18.3 meters) before retreating into the left entry 150 in preparation for the next cut. Cuts to the right are made to intersect the crosscut between the middle entry 152 and the left entry 150. Cuts to the left and right alternate with the two mobile roof supports following along the No. 1 entry 150 as the retreat sequence continues.

FIG. 11C shows the cuts to the left continuing but the cuts to the right changing orientation. On the first cut to the right (Cut #6 in FIG. 11), the distance between the No. 1 entry 150 and the crosscut approximately matches the length of the continuous miner 110 and the two roof supports 112. The second right-side cut (Cut #10 in FIG. 11) runs along the No. 1 entry and reduces the distance between the mined area and the No. 2 entry. The two mobile roof supports continue to follow along the No. 1 entry 150 as the retreat sequence continues.

FIGS. 11D and 11E show a similar sequence of cuts being made off the right entry 154.

FIG. 11F shows cuts from the middle entry 152 being used to mine the pillars with alternating right- and left-side cuts (Cut #21-Cut #28 in FIG. 11). The cuts made along the left entry 150 (see FIG. 11C) and the No. 3 entry (see FIG. 11E) reduce the width of the pillars to allow the alternating right- and left-side cuts from the middle entry 152 to be performed without additional roof protection beyond the roof supports 112 and the mobile roof supports 149. This approach is anticipated to provide higher production rates than systems that need roof bolting during the retreat sequence. Like the development sequence, the retreat sequence is also anticipated to provide higher productions rates than approaches that include higher numbers of equipment moves.

FIG. 11G shows the continuous miner 110 and the roof supports 112 before they pull back down the No. 2 entry 152 in preparation for repeating the process illustrated in FIGS. 11A-11H. The remaining portions of the pillars by the mobile roof supports 149 in the middle entry 152 will often be left in place.

A number of embodiments of mining systems and methods have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, FIG. 12 shows the cuts for another retreat mining sequence. This approach leaves additional portions or the formation in place to provide additional support near intersections where roof stresses will be greatest. Accordingly, other embodiments are within the scope of the following claims. 

What is claimed is:
 1. A mining system comprises: a continuous miner; a movable roof support; a roof bolter; and a flexible conveyor train positioned with its front end located under the roof support and extending underneath the roof bolter.
 2. The system of claim 1, wherein the roof support comprises: two tracks; legs mounted on the two tracks; and a canopy supported by legs and the two tracks; wherein the legs and the tracks are spaced apart to define a gap that is wide enough to receive the flexible conveyor train through the gap.
 3. The system of claim 2, wherein the gap is at least 14 feet (4.3 meters).
 4. The system of claim 2, wherein the legs comprise hydraulic pistons.
 5. The system of claim 2, wherein the moveable roof support is a first roof support and the mining system comprises a second moveable roof support.
 6. The system of claim 5, comprising chains extending between a canopy of the first moveable roof support and a canopy of the second moveable roof support
 7. The system of claim 2, wherein the moveable roof support comprises a canopy and an extendable portion movable between an extended position and a retracted position by a piston.
 8. The system of claim 1, wherein the roof bolter comprises: two tracks; a canopy supported by the two tracks; wherein the tracks are spaced apart to define a gap that is wide enough to receive the flexible conveyor train through the gap.
 9. The system of claim 8, wherein the gap is at least 14 feet (4.3 meters).
 10. The system of claim 8, wherein the roof bolter comprises six drill masts.
 11. The system of claim 8, wherein the canopy is supported by legs mounted on the two tracks.
 12. The system of claim 11, wherein the legs comprise hydraulic pistons.
 13. The system of claim 8, wherein the canopy is supported by a scissors lift system mounted on the two tracks.
 14. The system of claim 8, wherein the canopy comprises a work platform.
 15. The system of claim 14, wherein the roof support comprises four drill masts pivotably mounted to the working platform and oriented upwards to install roof bolts.
 16. The system of claim 15, wherein the roof support comprises two drill masts that are pivotably mounted to the working platform and oriented sideways to install rib bolts.
 17. A method of mining comprising: positioning a first movable roof support between a continuous miner and a roof bolter; and extending a flexible conveyor train between tracks of the roof bolter and between tracks of the first movable roof support and positioning a hopper of the flexible conveyor train to receive output of the continuous miner. 